<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      button {
        font-size: 24px;
      }
    </style>
  </head>
  <body>
    <button onclick="alert('Hello,这是标签内')">标签内</button>

    <button>内部引用</button>
    <button>外部引用</button>
    <script>
      document.querySelector("button").onclick = function () {
        alert("Hello,内部引用");
      };
    </script>
    <script src="./JS/test.js"></script>
  </body>
</html>
